They demand their customers pay licencing fees to licenses they don't own, like the Java language itself which is not subject to copyright under US law.
The suit against Google was filed within a month of the Sun acquisition, it was part of their reasoning for buying Sun in the first place: so that they can sue Java users and get tons of money for nothing.
Sun would have tried to squash Google just as they did before with Microsoft, but they were out of cash, sadly as we could have gotten a proper JavaSE mobile platform instead of the craziness of Android development and incompatibilities with OpenJDK.
The suit against Google was filed within a month of the Sun acquisition, it was part of their reasoning for buying Sun in the first place: so that they can sue Java users and get tons of money for nothing.